Previous studies have documented high rates of comorbidity of other
psychiatric conditions among individuals with bipolar disorders (BD).
[1] One study estimated that obsessive-compulsive disorders (OCD)
accounted for 21% of all comorbidities in BD. [2] There is continuing
debate about whether (a) these are two independent conditions that can
co-occur or (b) OCD is a specific subtype of BD. Regardless of the
interrelationship of the two conditions, the comorbid occurrence of
these two types of symptoms can cause a clinical dilemma because
selective serotonin reuptake inhibitors (SSRIs)--which are quite
commonly used to treat OCD--increases the risk of precipitating manic
symptoms. [3-6]

The OCD symptoms that occur in individuals with BD often occur
during the depressive episodes or during the intervals between episodes
of depressive or manic symptoms. [7,8] This timing of OCD symptoms
during BD is consistent with the cyclic nature of BD and suggests shared
biological mechanisms between the two disorders. In support of this
hypothesis, a study using Positron Emission Tomography (PET) found that
in untreated persons with BD the serotonin-transporter binding potential
in the insular and dorsal cingulate cortex was higher among BD patients
with pathological obsessions and compulsions than among BD patients
without such symptoms. [9] Moreover, a linkage study found that compared
to OCD patients without comorbid BD, patients with comorbid OCD and BD
were more likely to have a family history of mood disorders but less
likely to have a family history of OCD. [10] However, another study
found no significant difference in the rates of a positive family
history of OCD between patients with OCD alone and those with comorbid
OCD and BD. [11] Further support for the hypothesized common etiology
comes from a preliminary molecular genetic study which found that
hyperpolarization activated cyclic nucleotide-gated channel 4 (HCN4) is
a common susceptible locus for both mood disorders and OCD, but further
studies with larger sample sizes are needed to replicate this finding.
[12]

The presence of OCD in BD complicates the clinical presentation.
Compared to patients with BD without comorbid OCD, those that have
comorbid BD and OCD often have a more severe form of BD, have more
prolonged episodes, are less adherent to medication, and are less
responsive to medication. Recent studies about comorbid BD and OCD have
reported the following:

(a) Temporal relationship. Some studies suggest that OCD is an
antecedent of BD, [10] but others report concurrent onset of OCD and BD.
[13,14]

(b) Course of disease. In 44% of patients with comorbid BD and OCD
the episodes are cyclic. [15] The course of disease is more chronic
among BD patients with OCD compared to those without comorbid OCD.
[16,17] OCD is more commonly observed in patients with Type II BD, among
whom the prevalence of OCD has been reported to be as high as 75%. [18]

(c) Compulsive behaviors. The most commonly reported compulsions
among patients with comorbid OCD and BD are compulsive sorting, [14 19
20 21] controlling or checking, [20] repeating behaviors, [13 22]
excessive washing, [20] and counting. [19] Obsessive reassurance-seeking
is also commonly reported in these patients. [23] In children and
adolescents with BD, compulsive hoarding, impulsiveness, [24] and
sorting [25] are more common.

(d) Substance and alcohol abuse. A study found a higher prevalence
of sedative, nicotine, alcohol, and caffeine use among individuals with
comorbid OCD and BD compared to those with BD without OCD. [14]
Similarly, compared to OCD patients without comorbid mood disorders,
those with a comorbid mood disorder were more likely to have a substance
abuse diagnosis (OR=3.18, 95%CI=1.81-5.58) or alcohol abuse diagnosis
(OR=2.21, 95%CI=1.34-3.65). [11,13,26,27,28]

(e) Suicidal behaviors. Compared to BD patients without OCD, a
greater proportion of patients with both disorders had a lifetime
history of suicidal ideation and suicide attempts. [2,11,13,29,30]

The clinical management of comorbid OCD and BD requires first
focusing on stabilizing the patient's mood, which requires the
combined use of multiple medications such as the use of lithium with
anticonvulsants or atypical antipsychotic medications such as
quetiapine; [31,33] adjunctive treatment with aripiprazole may be
effective for the comorbid OCD symptoms. [4] In the case of OCD comorbid
with type II BD, after full treatment of the mood symptoms with mood
stabilizers the clinician can, while monitoring for potential drug
interactions, cautiously try adjunctive treatment with antidepressants
that are effective for both depressive symptoms and OCD symptoms and
that have a low risk of inducing a full manic episode, including the
selective serotonin reuptake inhibitors (SSRIs): fluoxetine,
fluvoxamine, paroxetine, and sertraline. [32,35]

In summary, BD comorbid with OCD may be etiologically distinct from
either of the disorders. Clinicians should pay attention to its complex
clinical manifestations and carefully consider the treatment principles
outlined above.

Conflict of Interest

The authors declare no conflict of interest related to this
manuscript.

Funding

There was no funding support provided for the preparation of this
report.

Dr. Peng obtained his Doctoral Degree in Medicine (M.D.) from the
Fudan University School of Medicine in 2006. He is currently the vice
director of the Mood Disorder Unit of the Shanghai Mental Health Center
where he works as an attending physician. His main research interests
are clinical and neuroimaging studies on mood disorders.